A&A 405, 585–590 (2003) Astronomy DOI: 10.1051/0004-6361:20030599 & c ESO 2003 Astrophysics Interstellar extinction in the direction of the Aquila Rift V. Straiˇzys1,K.Cernisˇ 1, and S. Bartaˇsi¯ut˙e1;2 1 Institute of Theoretical Physics and Astronomy, Vilnius University, Goˇstauto 12, Vilnius 2600, Lithuania e-mail:
[email protected] 2 Astronomical Observatory of Vilnius University, Ciurlionioˇ 29, Vilnius 2009, Lithuania e-mail:
[email protected] Received 28 February 2003 / Accepted 14 April 2003 Abstract. The distance dependence of interstellar extinction in the direction of the Aquila Rift is investigated using 473 stars observed in the Vilnius photometric system. The front edge of the dark clouds in the area is found to be at 225 55 pc and ± the thickness of the cloud system is about 80 pc. The maximum extinction AV in the clouds is close to 3.0 mag. Two stars with larger extinction are found and discussed. Since the new distance of the clouds is larger than the previously accepted distance, the cloud system mass should be increased to 2:7 105 M which is close to the virial mass estimated from the CO velocity × dispersion. Additional arguments are given in favor of the genetic relation between the Serpens and the Scorpio-Ophiuchus dark clouds. Key words. stars: fundamental parameters – ISM: dust, extinction – ISM: clouds – ISM: individual objects: Aquila Rift – ISM: individual objects: Serpens molecular cloud 1. Introduction Stars and other sources in the area have been well cov- ered by the infrared surveys: by IRAS in the far infrared and Starting from Cygnus, in the direction of the Galactic center the by 2MASS in the JHK range.